The study of neural plasticity (i.e., the ways in which the nervous system changes in response to an animal's experience) remains a fundamental problem in neurobiology. This proposal deals with the regulation of two classes of proteins that play essential roles in synaptic physiology--the enzymes which catalyze the synthesis of specific neurotransmitters and the receptors which mediate the post-synaptic effects of these transmitters. The primary goals of this research are 1. to study the role of neural and humoral factors in the regulation of tyrosine hydroxylase and dopamine beta hydroxylase in the cell bodies and terminals of adrenergic neurons, 2. to localize in the spinal cord the cell bodies of the preganglionic neurons which innervate the superior cervical ganglion and to study the regulation of choline acetyltransferase activity and the transport of this enzyme in these neurons, and 3. to use alpha-bungarotoxin to characterize the ganglionic nicotinic receptor in the avian ciliary ganglion and to study the long-term regulation of this receptor. Most of the experiments will be performed in peripheral autonomic ganglia due to their experimental accessibility and to the vast amount of knowledge which has accumulated about them. In addition, certain experiments will be concerned with establishing whether similar regulatory processes occur in the central nervous system. These studies should help to elucidate the mechanisms involved in the regulation of these important proteins both during development and during adult life.